The present invention relates to the use of certain dirt-removing polymers for enhancing the cleaning performance of laundry detergent compositions when used for washing textiles, especially textiles which consist of or contain cotton, and also to laundry detergent compositions which comprise such dirt-removing polymers.
Laundry detergent compositions, as well as the ingredients vital to the washing operation, such as surfactants and builder materials, generally further comprise constituents which may be grouped together under the heading of wash auxiliaries and which encompass such different categories of active chemical entities as foam regulators, soil antiredeposition agents, bleaches, bleach activators and color transfer inhibitors. Such auxiliaries also include substances which endow the laundry fiber with dirt-rejecting properties and which, if present during the washing process, augment the dirt-removing ability of the other laundry detergent constituents. The same applies mutatis mutandis to cleaning compositions for hard surfaces. Such dirt-removing substances are often known as soil release agents or, on account of their ability to render the treated surface, of the fiber for example, dirt-rejecting, as soil repellents. Owing to their chemical similarity to polyester fibers in the case of textiles composed of this material, particularly effective soil release agents are copolyesters which comprise dicarboxylic acid units, alkylene glycol units and polyalkylene glycol units. Soil release copolyesters of the kind mentioned and also their use in laundry detergent compositions have been known for a fairly long time.
For instance, German Offenlegungsschrift DT 16 17 141 describes a washing process which utilizes polyethylene terephthalate-polyoxyethylene glycol copolymers. The German Offenlegungsschrift DT 22 00 911 concerns laundry detergent compositions which comprise nonionic surfactant and an interpolymer from polyoxyethylene glycol and polyethylene terephthalate. German Offenlegungsschrift DT 22 53 063 mentions acidic textile-finishing compositions which comprise a copolymer from a dibasic carboxylic acid and from an alkylene or cycloalkylene polyglycol and also optionally from an alkylene or cycloalkylene glycol. Polymers from ethylene terephthalate and polyethylene oxide terephthalate wherein the polyethylene glycol units have molecular weights from 750 to 5000 and the molar ratio of ethylene terephthalate to polyethylene oxide terephthalate is in the range from 50:50 to 90:10 and their use in laundry detergent compositions are described in the German patent DE 28 57 292. Polymers having molecular weight 15 000 to 50 000 from ethylene terephthalate and polyethylene oxide terephthalate wherein the polyethylene glycol units have molecular weights from 1000 to 10 000 and the molar ratio of ethylene terephthalate to polyethylene oxide terephthalate is in the range from 2:1 to 6:1 can be used in laundry detergent compositions, according to German Offenlegungsschrift DE 33 24 258. European patent EP 066 944 concerns textile-treating compositions which comprise a copolyester from ethylene glycol, polyethylene glycol, aromatic dicarboxylic acid and sulfonated aromatic dicarboxylic acid in certain molar ratios. European patent EP 185 427 discloses methyl- or ethyl-endcapped polyesters having ethylene and/or propylene terephthalate and polyethylene oxide terephthalate units and laundry detergent compositions which comprise such soil release polymer. European patent EP 241 984 concerns a polyester which, as well as oxyethylene groups and terephthalic acid units, also comprises substituted ethylene units and also glycerol units. European patent EP 241 985 discloses polyesters which, as well as oxyethylene groups and terephthalic acid units, comprise 1,2-propylene, 1,2-butylene and/or 3-methoxy-1,2-propylene groups and also glycerol units and are end group capped with C1- to C4-alkyl groups. European patent EP 253 567 concerns soil release polymers having a molar mass from 900 to 9000 from ethylene terephthalate and polyethylene oxide terephthalate, wherein the polyethylene glycol units have molecular weights from 300 to 3000 and the molar ratio of ethylene terephthalate to polyethylene oxide terephthalate is in the range from 0.6 to 0.95. European patent application EP 272 033 discloses at least partly C1-4-alkyl- or acyl-endcapped polyesters having polypropylene terephthalate and polyoxyethylene terephthalate units. European patent EP 274 907 describes sulfoethyl-endcapped terephthalate soil release polyesters. In European patent application EP 357 280 soil release polyesters having terephthalate, alkylene glycol and poly-C2-4-glycol units are prepared by sulfonation of unsaturated end groups. German patent application DE 26 55 551 describes the reaction of such polyesters with polymers which contain isocyanato groups and the use of the thus prepared addition polymers as soil antiredeposition agents for the washing of synthetic fibers. German patent DE 28 46 984 discloses laundry detergent compositions which comprise a soil release polymer which is a reaction product of a polyester with a prepolymer which is obtained from a diisocyanate and a hydrophilic nonionic macrodiol and contains terminal isocyanate groups.
Polymers known from this voluminous prior art have the disadvantage that they are only insufficiently effective, if at all, in the case of textiles which do not consist of polyester or at least not overwhelmingly so. But textiles today consist to a large part of cotton or cotton-polyester blends, so that there is a need for soil release polymers which perform better against greasy stains on such textiles.
It has surprisingly been found that this object is achieved by the use of certain urethane-based polymers. As used herein, the indefinite articles “a” and “a” are synonymous with the phrases “one or more” and “at least one,” unless specifically defined otherwise.